Pump inlet guard



y 8, 1956 LE ROY A. DlFFORD 2,744,466

PUMP INLET GUARD Filed Sept. 25, 1952 2 Sheets-Sheet 1 EZFETIZLET LeFog A. Diffora y 1956 LE ROY A. DIFFORD 2,744,466

PUMP INLET GUARD Filed Sept. 25. 1952 2 Sheets-Sheet 2 1620 A. .Diffom L LH United States Patent PUMP INLET GUARD Le Roy A. Dilford, East Cleveland, Ohio, assignor to Thompson Products, Inc., a corporation of Ohio Application September 25, 1952, Serial No. 311,345

Claims. (Cl. 103-103) This invention relates to a deformable guard for preventing flow of extraneous matter without impeding flow of fluid. Specifically, this invention relates to helically coiled wire guard for pump inlets which is arranged to span opposed surfaces adjacent the pump inlet and follow all irregularities in said surfaces to prevent occurrence of any gaps.

While the invention will hereinafter be specifically described as embodied in a guard for a submerged boost er pump in a fuel cell, it will be understood that the guard of this invention is suitable for use in preventing passage of undesired solid matter without impeding liquid flow and while maintaining a very low pressure drop across the screening section of the device.

In accordance with this invention, a retaining annulus or washer has a helically wound Wire secured to one face thereof. The coils of the helix depend from the washer and form a deformable ring. When the coils are pressed against a surface, they will deform into mating conformity with the surface so that no gaps will be provided between the coils and the surface. Flow into or out of the washer occurs through the spaces between the coil. The spaces can be controlled as desired to form a filter of predetermined fineness. The washer or annulus is preferably provided with bolt holes for attachment to the inlet mouth of a pump. In a preferred installation, the pump will have a downward opening inlet in opposed relation to a sump plate. The annulus or washer will be secured to the pump inlet with the coils pressed against the sump plate. Since the sump plate is curved and may have irregular surfaces, the coils will be deformed into conformity with such surfaces by a pressing load imposed thereon. This load will vary depending upon manufacturing variances in the space between the pump mouth and the sump. The inherent resiliency of the coils will maintain tight press loaded contact between the sump and the coil carrying washer or plate. Fluid cannot, therefore, flow into or out of the pump except through the spaces between the coils or convolutions. Since these spaces can be controlled to suit particular installations, the spring helix will have a filtering function of desired capacity.

It is, therefore, an object of this invention to provide a filter or guard composed of deformable coils of wire or the like which are loaded into conformity with opposed surfaces and which accomodate free fluid flow between the convolutions thereof.

Another object of this invention is to provide a pump inlet guard composed of a helically coiled wire.

Another object of this invention is to provide a filtering screen in the form of an annulus of helically coiled wire having spaces between the coils of desired filtering capacity and having the coils loaded between opposed surfaces to maintain firm engaging contact with the surfaces.

Another object of the invention is to provide a pump inlet guard for submerged booster pumps having downwardly opening inlets and opposed sump plates wherein a ring of helically coiled wire is loaded between the 'ice inlet and the sump plate to form an annular screen preventing flow of extraneous matter into the pump while accommodating free flow of liquid into the pump.

A specific object ofthis invention is to provide a pump inlet guard having a flat metal washer carrier plate and a ring of helically coiled wire depending from one face of the plate.

Other and further objects of this invention will be apparent to those skilled in the art from the following detailed description of the annexed sheet of drawings which, by way of a preferred embodiment, illustrates one example of the invention.

On the drawings:

Figure 1 is a fragmentary vertical cross-sectional view with parts in elevation of a booster pump for an aircraft fuel system submerged in an aircraft fuel cell.

Figure 2 is a bottom plan view of the pump shown in Figure 1 with parts broken away to illustrate underlying parts.

Figure 3 is a plan view of the pump inlet guard of this invention.

Figure 4 is a cross-sectional view of the guard of Figure 3 taken along the line IV-IV of Figure 3.

Figure 5 is a fragmentary side elevational view showing the manner in which the guard of this invention follows the contour of an irregular surface when pressed thereagainst.

Figure 6 is a fragmentary bottom plan view of the in let of a booster pump equipped with a modified guard according to this invention.

Figure 7 is a vertical cross-sectional view taken along the line VII-VII of Figure 6 and also showing a portion of the sump of the pump underlying the inlet.

As shown on the drawings:

In Figure 1, the reference numeral 10 designates generally a pump and motor unit mounted inside of an aircraft fuel cell 11. The fuel cell 11 has a bottom wall 12 with an aperture 13 freely receiving the pump 10 therethrough. A mounting ring 14 is disposed on the bottom wall 12 of the cell 11 to surround the opening 13. The pump unit 10 has a mounting plate 15 underlying the cell wall 12 and receiving mounting screws 16 at spaced intervals around the periphery thereof to ex tend therefrom through the bottom wall of the tank into the mounting ring 14 so that the unit 10 will be fixedly held in the bottom of the tank with the plate 15 closing the opening 13.

The plate 15 has a dished central portion 17 forming an inlet sump to the pump. This sump 17 is below the level of the bottom wall 12 of the fuel cell so that the inlet of the pump can be mounted close to the bottom of the cell and thereby be submerged in fuel in the cell until the cell is emptied.

The unit 10 includes a pump casing 18 with alaterally projecting boss portion 19 terminating in an upstanding open-ended pedestal or nipple 20 which is mounted on the base plate 15 to carry the unit 10 on the plate.

Posts 21 extend upwardly from the pump casingqlfi to a head 22 on which is mounted a motor 23 carried by a casing 24. A motor shaft 25 extends through bearings 26 in the head 22 and through a seal 27 in the bottom end of the head to a pump impeller 28 having a top hub portion 29 secured on the shaft as by means of a nut 30 and key 31. The hub 29 has a ring of depending pumping vanes 32 on the bottom face thereof.

The pump casing 18 has a central open-ended passage therethrough receiving a throat ring 33 in the bottom open end thereof to underlie and surround the pumping vanes 32. The vanes 32 discharge peripherally at their upper ends into a volute 34 in the pump casing. This volute has a tangential outlet 35 discharging into the nipple 20. The hub 29 rotates in a diffuser ring 36 mounted in the upper open end of the central passageway of the pump casing. This diffuser ring provides an annular diffusion gap 37 around the hub 29 and vapors released by the pumping vane 32 are diffused back into the fuel cell through this gap 37. The vanes 32 are shaped so as to centrifugally discharge fully liquid fuel into the volute 34 and to induce flow of gas or vapor rich fluids through the gap 37 for discharge back into the tank.

The pump casing 18 can be surrounded by a cylindrical screen 38 which depends from the head 22 to the sump 17. This screen being stiff does not readily deform into conformity with the surface of the sump forming portion 17 of the base plate so that frequently gaps are provided accommodating passage of extraneous matter such as washers, nuts, chips and the like finding their way into the fuel cell. Since such material would damage the pump, it is essential that it be screened out and that the screening operation have no impeding effect on the flow of the fuel to the pump inlet.

Therefore, the pump, in accordance with this invention, is provided with the inlet guard 40. This guard is composed of a flat metal washer 41 fitting on the face of the throat ring 33 of the pump and having perforated ears 41a registering with the bolt holes in the throat ring 33 to receive therethrough the same mounting bolts 42 which are used to secure the throat ring to the inlet mouth of the pump casing.

The washer 41 presents a flat bottom face and a helically wound wire coil 43 has the coils thereof held against this bottom face by kerfs 44 cut out from the washer to underlie the top portion of a wire coil. Other securing means such as welding, brackets or the like can be used. Three kerfs 44 are shown in Figure 3. This provides an annulus of wire coils 43a which are spaced apart to provide flow gaps 45 of desired size.

The coils 43a in their undeformed state are substantially circular as shown in Figure 4. However, the coils have a free diameter somewhat greater than the space between the bottom of the sump 17 and the washer 41 so as to be pressed against the sump 17 and be loaded thereby. The coils, as shown in Figure 5, will thereupon be deformed into conformity with the surface of the sump and will tightly press against this surface to eliminate any gaps accommodating passage of extraneous matter. The coils will be somewhat flattened due to their pressed engagement against the sump wall but they will maintain an inherent resiliency due to their normal tendency to spring back into circular shape, so that a tight fit will be maintained.

In the modification shown in Figures 6 and 7, the booster pump unit has an inlet guard 50 thereon which is somewhat different from the guard shown in Figures 1 to 5. This guard includes a split flat spring washer 51 receiving a helically wound wire coil spring 52 therearound. The coil spring is assembled on the split washer by feeding the coils of the spring over one end of the washer until the washer is completely within the coils. The washer 51 has an inside diameter such that the coil spring is retained in an annulus of desired diameter with the end coils of the spring abutted together as at 53. The washer 51 will therefore lie in the center of the spring coil to hold it in annular form.

Three posts 54 are assembled on the inlet of the pump, using the same screws 55 which fasten the throat ring 33 to the bottom of the casing 18. Each post 54 has a peripheral groove 56 receiving the outer edge of the washer 51 to mount the guard around the inlet mouth of the pump with the coils tightly abutting both the throat ring and the bottom of the sump and being deflected into conformity therewith.

The ends of the split washer 51 are overlapped as shown at 57 and the washer is sufliciently resilient so that the guard assembly can be snapped into the grooves 56 of the posts after the posts are in position. The coils of the spring 52 will straddle the posts as shown in Figure 6 and will serve to protect the pump inlet from foreign matter without interfering with free fluid flow into the pump. In addition, the washer 51 inside the coil spring divides the passages between the coils into upper and lower compartments and protects against passage of flat foreign matter which might meet the coils in a vertical plane. For example, it is conceivable that a flat piece of metal might slide flatwise under the screen 38 of the pump and then be vibrated into vertical position between the coils. The insert washer 51 will thereupon prevent passage of the piece into the pump throat.

From the above description it will be understood that this invention provides a deformable coiled wire filter or screen for surrounding the inlet of a pump and adapted to be deformed into conformity with surfaces opposing the pump inlet so as to tightly engage the surfaces and prevent formation of gaps which will accommodate flow of extraneous matter.

I claim as my invention:

1. A pump inlet guard which comprises a flat metal washer having apertured mounting means at spaced intervals around the periphery thereof and presenting a flat face, a helix of wire having circular coils afiixed to the flat face of the washer and depending therefrom to form deformable loops in spaced relation around the washer, said loops being deformable into conformity with an opposed surface.

2. A pump inlet guard for cooperating with opposed pump surfaces and which comprises a flat split spring washer, a coil spring wound around the washer to provide an annulus of spaced coils with the washer therein, and means for mounting the washer on a pump to hold the coils against opposed pump surfaces to stop passage of solids larger than the spaces between the coils and said washer dividing said spaces into compartments to prevent passage of solids which are turned edgewise to fit between the coils.

3. In a fluid impeller structure including an impeller chamber body having an inlet and a fluid supply opening communicating with said inlet, a guard generally between the inlet and the fluid supply opening comprising convolutions of wire and the like coiled generally around said inlet and resiliently engaged with and confined by said body with the axis of the coils lying generally in a plane perpendicular to the axis of the pump inlet and with the coils directly in the path of fluid flowing from said opening to trap between said coils solid particles in advance of entry of fluid in said impeller chamber.

4. In a fluid impeller structure including an impeller chamber body having an inlet and a fluid supply opening communicating with said inlet, a guard generally between the inlet and the fluid supply opening comprising convolutions of wire and the like coiled generally around said inlet and resiliently engaged with and confined by said body with the coils directly in the path of fluid flowing from said opening to trap between said coils solid particles in advance of entry of fluid in said impeller chamber, said coils being in the form of an annlus generally concentric with said inlet, the plane of which annulus is at right angles to the flow of fluid through said inlet and in which plane the fluid flows between said coils.

5. In a fluid impeller structure including an impeller chamber body having an inlet and a fluid supply opening communicating with said inlet, a guard generally between the inlet and the fluid supply opening comprising con volutions of wire and the like coiled generally around said inlet and resiliently engaged with and confined by said body with the coils directly in the path of fluid flowing from said opening to trap between said coils solid particles in advance of entry of fluid in said impeller chamber, said guard coils being loosely wound around an annular core for holding the coils generally but loosely in an annular shape.

6. In a fluid impeller structure including an impeller chamber body having an inlet and a fluid supply opening communicating with said inlet, a guard generally between the inlet and the fluid supply opening comprising convolutions of wire and the like coiled generally around said inlet and resiliently engaged with and confined by said body with the coils directly in the path of fluid flowing from said opening to trap between said coils solid particles in advance of entry of fluid in said impeller chamber, and means connected to said guard coils for holding the coils in an annular shape.

7. In a fluid impeller structure including an impeller chamber body having an inlet and a fluid supply opening communicating with said inlet, a guard generally between the inlet and the fluid supply opening comprising convolutions of wire and the like coiled generally around said inlet and resiliently engaged with and confined by said body with the coils directly in the path of fluid flowing from said opening to trap between said coils solid particles in advance of entry of fluid in said impeller chamher, a first means connected to said guard coils for holding the coils in predetermined shape, and a second supported means connecting said first means to said structure for positively positioning said guard coils with relation to the pump inlet.

8. In a fluid impeller structure including an impeller chamber body having an inlet and a fluid supply opening communicating with said inlet, a guard generally between the inlet and the fluid supply opening comprising convolutions 'of wire and the like coiled generally around said inlet and resiliently engaged with and confined by said body with the coils directly in the path of fluid flowing from said opening to trap between said coils solid particles in advance of entry of fluid in said impeller chamber, and means connected to said guard coils for loosely holding the coils in an annular shape so that the diameter of the coils may be resiliently varied to accommodate variable sized openings in the body that confines the coils.

9. A pump structure inlet port guard for cooperation with opposed structure surfaces and which comprises, a spring washer, a coil spring connected to the washer to maintain the coils in a predetermined relationship, and means for mounting the washer on a pump to hold the coils against opposed pump surfaces to stop passage of solids between the coils.

10. A pump structure inlet port guard for cooperation with opposed structure surfaces and which comprises a vsupporting member having mounting means, a coiled length of wire carried on said supporting member by said mounting means to form deformable loops in spaced relation around the inlet port, said loops being deformable into conformity with the opposed surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 850,379 Lasher Apr. 16, 1907 2,037,127 Ford Apr. 14, 1936 2,489,682 Smith et al. Nov. 29, 1949 2,507,018 Jewett et a1. May 9, 1950 2,604,077 Nast July 22, 1952 FOREIGN PATENTS 114,366 Great Britain Apr. 4, 1918 

